i have 1968 skidoo olypmic 370 opposed twin im looking to order top end gaskets for it from royal distributing now they tell me there is not a listing for that model now i was just wondering if any of these other models would be the same olympic 300, 300s,340e,399/400/e/es,440/s,440,olympic plus 440 (twin) or super olympic 300 or there is a set on ebay 165cc 370 rotax gasket